The present invention relates to electronic devices, and more particularly, to an improved procedure for estimating the current consumption of a battery used in conjunction with the electronic device.
Most portable electronic devices today utilize a rechargeable battery as a power source. As such, the display of the electronic device provides the user with a visual display of the residual power level of the rechargeable battery in order to avoid unexpected loss of power during use of the electronic device. By alerting the user of the residual power level, the user can initiate recharging of the device, terminate a call on a mobile station, or save data on a laptop computer prior to power loss.
The electronic devices, such as mobile stations, PDAs, or laptops, generally calculate a residual power level at a variety of time intervals. At power-up, most electronic devices calculate the residual power left in the battery. Then, at predetermined time intervals, or in response to certain actions, the electronic device recalculates the residual power level.
In U.S. Pat. No. 5,434,508, the residual battery power is calculated for a laptop computer having a normal operation mode and a suspended operation mode. The laptop computer includes a battery pack that comprises a calculator unit. The calculator unit determines an electric current flowing through a current detecting resistor. Following the determination of the electric current, current consumption data is read from a mode table. The mode table lists the possible modes and the current consumed for each particular mode. The residual battery power is then calculated by the calculator unit based on the information provided by the mode table.
In an alternative approach, in U.S. Pat. No. 5,784,295, the residual battery power is calculated for a mobile station capable of using a backlight. The mobile station consumes more battery power by operating with the backlight on, as opposed to with the backlight off. The residual power level is calculated by first determining the battery voltage when the backlight is on. Then the battery voltage is determined when the backlight is off. The residual power level is calculated by utilizing the difference of the determined battery voltages.
Algorithms for calculating the residual battery power take into account the operational mode of the electronic device, i.e. whether the device is in normal or idle mode for a mobile station, as well as whether the device is transmitting information. However, there is a need for even more accurate residual battery power estimation.
The present invention provides more accurate estimates of residual battery power by including power used during reception when calculating the residual power level. The method and apparatus of the present invention estimate the remaining battery power and estimate the charge consumed when receiving incoming bursts. The charge consumed when receiving incoming bursts is calculated by determining the time duration of the received burst and reading a value stored in memory related to the charge consumed by receiving the burst. Alternatively, each received burst may be counted by a counter. The estimated charge consumed when receiving bursts is calculated based on the values of the counters, or the calculated time duration, and the value stored in memory related to the charge consumed. The remaining battery power is determined by subtracting the estimated charge consumed from the previous remaining battery power estimate. If the electronic device has transmitted data, then the charge consumed by the transmissions is also subtracted from the previous remaining battery power estimate.